diff --git a/ChangeLog b/ChangeLog
index fa364c4a..1537081d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -29,6 +29,10 @@ Arnold Krille
 ---------------------------
   Jackdmp changes log
 ---------------------------
+
+2010-05-27 Stephane Letz  <letz@grame.fr>
+
+	* In JackCoreAudioDriver, move code called in MeasureCallback to be called once in IO thread.
 
 2010-05-07 Stephane Letz  <letz@grame.fr>
 
diff --git a/common/JackError.cpp b/common/JackError.cpp
index 905bbef8..5338bd3c 100644
--- a/common/JackError.cpp
+++ b/common/JackError.cpp
@@ -27,17 +27,15 @@
 
 using namespace Jack;
 
-void change_thread_log_function(jack_log_function_t log_function)
+static bool change_thread_log_function(jack_log_function_t log_function)
 {
-    if (!jack_tls_set(JackGlobals::fKeyLogFunction, (void*)log_function))
-    {
-        jack_error("failed to set thread log function");
-    }
+    return (jack_tls_get(JackGlobals::fKeyLogFunction) == NULL 
+            && jack_tls_set(JackGlobals::fKeyLogFunction, (void*)log_function));
 }
 
-SERVER_EXPORT void set_threaded_log_function()
+SERVER_EXPORT bool set_threaded_log_function()
 {
-    change_thread_log_function(JackMessageBufferAdd);
+    return change_thread_log_function(JackMessageBufferAdd);
 }
 
 void jack_log_function(int level, const char *message)
diff --git a/common/JackError.h b/common/JackError.h
index e16a65b2..27a7e323 100644
--- a/common/JackError.h
+++ b/common/JackError.h
@@ -53,10 +53,9 @@ extern "C"
 
     typedef void (* jack_log_function_t)(int level, const char *message);
 
-    void change_thread_log_function(jack_log_function_t log_function);
     void jack_log_function(int level, const char *message);
    
-    SERVER_EXPORT void set_threaded_log_function();
+    SERVER_EXPORT bool set_threaded_log_function();
 
 #ifdef __cplusplus
 }
diff --git a/macosx/coreaudio/JackCoreAudioDriver.cpp b/macosx/coreaudio/JackCoreAudioDriver.cpp
index f4b24782..f1b62dc7 100644
--- a/macosx/coreaudio/JackCoreAudioDriver.cpp
+++ b/macosx/coreaudio/JackCoreAudioDriver.cpp
@@ -194,6 +194,22 @@ OSStatus JackCoreAudioDriver::Render(void *inRefCon,
     driver->fActionFags = ioActionFlags;
     driver->fCurrentTime = (AudioTimeStamp *)inTimeStamp;
     driver->fDriverOutputData = ioData;
+    
+    // Setup threadded based log function once...
+    if (set_threaded_log_function()) {
+        
+        jack_log("set_threaded_log_function");
+        JackMachThread::GetParams(pthread_self(), &driver->fEngineControl->fPeriod, &driver->fEngineControl->fComputation, &driver->fEngineControl->fConstraint);
+        
+        if (driver->fComputationGrain > 0) {
+            jack_log("JackCoreAudioDriver::Render : RT thread computation setup to %d percent of period", int(driver->fComputationGrain * 100));
+            driver->fEngineControl->fComputation = driver->fEngineControl->fPeriod * driver->fComputationGrain;
+        }
+        
+        // Signal waiting start function...
+        driver->fState = true;
+    }
+    
     driver->CycleTakeBeginTime();
     return driver->Process();
 }
@@ -221,33 +237,6 @@ int JackCoreAudioDriver::Write()
     return 0;
 }
 
-// Will run only once
-OSStatus JackCoreAudioDriver::MeasureCallback(AudioDeviceID inDevice,
-        const AudioTimeStamp* inNow,
-        const AudioBufferList* inInputData,
-        const AudioTimeStamp* inInputTime,
-        AudioBufferList* outOutputData,
-        const AudioTimeStamp* inOutputTime,
-        void* inClientData)
-{
-    JackCoreAudioDriver* driver = (JackCoreAudioDriver*)inClientData;
-    AudioDeviceStop(driver->fDeviceID, MeasureCallback);
-    
-    jack_log("JackCoreAudioDriver::MeasureCallback called");
-    JackMachThread::GetParams(pthread_self(), &driver->fEngineControl->fPeriod, &driver->fEngineControl->fComputation, &driver->fEngineControl->fConstraint);
-    
-    if (driver->fComputationGrain > 0) {
-        jack_log("JackCoreAudioDriver::MeasureCallback : RT thread computation setup to %d percent of period", int(driver->fComputationGrain * 100));
-        driver->fEngineControl->fComputation = driver->fEngineControl->fPeriod * driver->fComputationGrain;
-    }
-    
-    // Signal waiting start function...
-    driver->fState = true;
-    
-    // Setup threadded based log function
-    set_threaded_log_function();
-    return noErr;
-}
 
 OSStatus JackCoreAudioDriver::SRNotificationCallback(AudioDeviceID inDevice,
                                                     UInt32 inChannel,
@@ -1682,27 +1671,10 @@ int JackCoreAudioDriver::Start()
 {
     jack_log("JackCoreAudioDriver::Start");
     JackAudioDriver::Start();
-/*
-#ifdef MAC_OS_X_VERSION_10_5
-    OSStatus err = AudioDeviceCreateIOProcID(fDeviceID, MeasureCallback, this, &fMesureCallbackID);
-#else
-    OSStatus err = AudioDeviceAddIOProc(fDeviceID, MeasureCallback, this);
-#endif
-*/
-    OSStatus err = AudioDeviceAddIOProc(fDeviceID, MeasureCallback, this);
-    
-    if (err != noErr)
-        return -1;
 
-    err = AudioOutputUnitStart(fAUHAL);
+    OSStatus err = AudioOutputUnitStart(fAUHAL);
     if (err != noErr)
         return -1;
-
-    if ((err = AudioDeviceStart(fDeviceID, MeasureCallback)) != noErr) {
-        jack_error("Cannot start MeasureCallback");
-        printError(err);
-        return -1;
-    }
     
     // Waiting for Measure callback to be called (= driver has started)
     fState = false;
@@ -1724,15 +1696,6 @@ int JackCoreAudioDriver::Start()
 int JackCoreAudioDriver::Stop()
 {
     jack_log("JackCoreAudioDriver::Stop");
-    AudioDeviceStop(fDeviceID, MeasureCallback);
-/*
-#ifdef MAC_OS_X_VERSION_10_5
-    AudioDeviceDestroyIOProcID(fDeviceID, fMesureCallbackID);
-#else
-    AudioDeviceRemoveIOProc(fDeviceID, MeasureCallback);
-#endif
-*/
-    AudioDeviceRemoveIOProc(fDeviceID, MeasureCallback);
     return (AudioOutputUnitStop(fAUHAL) == noErr) ? 0 : -1;
 }
 
diff --git a/macosx/coreaudio/JackCoreAudioDriver.h b/macosx/coreaudio/JackCoreAudioDriver.h
index f17bbf19..9f827dfc 100644
--- a/macosx/coreaudio/JackCoreAudioDriver.h
+++ b/macosx/coreaudio/JackCoreAudioDriver.h
@@ -96,14 +96,6 @@ class JackCoreAudioDriver : public JackAudioDriver
                                UInt32 inNumberFrames,
                                AudioBufferList *ioData);
 
-        static OSStatus MeasureCallback(AudioDeviceID inDevice,
-                                        const AudioTimeStamp* inNow,
-                                        const AudioBufferList* inInputData,
-                                        const AudioTimeStamp* inInputTime,
-                                        AudioBufferList* outOutputData,
-                                        const AudioTimeStamp* inOutputTime,
-                                        void* inClientData);
-
         static OSStatus DeviceNotificationCallback(AudioDeviceID inDevice,
                 UInt32 inChannel,
                 Boolean	isInput,